Psoriasis, commonly called “oxhide lichen”, is a common and recurrent skin disease with chronic inflammation, and characterized by mica-like scale, red membrane sign, punctuate hemorrhage, with an incidence rate of about 0.123% in China. In recent years, the incidence of psoriasis shows tendency to ascend, and in the initial stage, psoriasis has an apparent seasonality, and presents severity in winter and light in summer. At present, the cause of disease is unknown, and effective therapeutic method is deficient.
Currently, psoriasis includes four types, i.e. psoriasisvulgaris, psoriasis arthropathica, erythroderma psoriaticum, and psoriasis pustulosa, in which psoriasisvulgarisaccounts for above 99% of psoriasis. Psoriasisvulgaris is an ordinary psoriasis, while the other three types are called specific psoriasis. According to experience summarization of famous doctors of traditional Chinese medicine in successive dynasties, psoriasisvulgaris is generally classified as four types, i.e. blood-heat type (blood-heat and wind-dryness type), blood-deficiency type (blood-deficiency and wind-dryness type), blood-dryness type, blood stasis type (thedermalhematomalikelytype); for special psoriasis, pustule type is generally discriminated as sepsis type (damp-heat and accumulated toxin type), and erythroderma type is poison and heat type (blood-heat toxic pattern), and joint type is cold-dampness or rheumatic arthralgia type.
Primary clinical manifestations of psoriasis vulgaris include white scale, shining thin film and punctuate hemorrhage. Main pathologic manifestations include: parakeratosis, visible microabscess (Munro's abscess) arising from neutrophilic granulocyte, granular layer thinning or vanishing; acanthosis, trochanterellus extension; blood vessels in dermal papilla distort and expand, and vessel wall slightly thickens; superior part of dermis is infiltrated by inflammatory cells of from mild to moderate. Psoriasis vulgaris is more common, and approximately occupied above 90%.
Psoriasis pustulosa is a type of psoriasis having more severe pathogenetic condition and divided into generalized psoriasis and localized psoriasis. In clinical, it is characterized by generalized erythema spreading whole body, as well as sterile pustules with a miliary size, and frequently accompanied by hyperpyrexia and increase of white blood cell and hypoproteinemia, even can threaten to life. This type is rarer in clinic, and accounts for about 0.77% of patients with psoriasis.
Tissue pathology of psoriasis is that epidermic keratinocytes cannot fully matured, and spaces between cell bundles fill with air and refract ray to form silver mica-like scale, as seen in clinical; intradermal papilledema swells and intrudes into epidermis, getting close to corneum layer, and in clinical, scraping scales may impair papilla blood vessels and produce punctuate hemorrhage. Medical doctors consider that development of psoriasis is mainly related to functional disorder of autoimmunity, metabolism and endocrine, but climatic change, labile mood, infection, trauma and so on are causative factors.
Pathogenesis of psoriasis is complex, and at present, it is not completely interpreted. The pathogenesis may roughly be summarized as follows: on the basis of certain genetic backgrounds, various causative agents stimulate the immune system of organisms, and cause functional disorders of immune system focusing on T cells. Inflammatory cells migrate to epidermis and locally infiltrate, resulting in part inflammation and paraplasm of keratinocytes, and finally resulting in occurrence of pathologic change of psoriasis.
Psoriasis is a common chronic inflammatory skin disease, with hyperplasia of keratinocytes, infiltration of inflammatory cells, and neovascularization as main pathologic changes, and is a commonly encountered disease and a frequently occurring disease in department of dermatology. Etiology of this disease is unknown, and its treatment is difficult, and it cannot be completely eradicated. Currently, western medicaments tretinoin and immunosuppressive agents are used to treat this disease, especially possessing advantages in controlling psoriasis activity, but they have problems including more adverse reactions and high recurrence rate following drug withdrawal, etc.